U.S. patent application number 13/932345 was filed with the patent office on 2013-11-07 for phosphorus-containing oligomer and method for producing the same, curable resin composition and cured product of the same, and printed wiring board.
The applicant listed for this patent is DIC Corporation. Invention is credited to Koji Hayashi, Yutaka Satou.
Application Number | 20130296597 13/932345 |
Document ID | / |
Family ID | 44482805 |
Filed Date | 2013-11-07 |
United States Patent
Application |
20130296597 |
Kind Code |
A1 |
Hayashi; Koji ; et
al. |
November 7, 2013 |
PHOSPHORUS-CONTAINING OLIGOMER AND METHOD FOR PRODUCING THE SAME,
CURABLE RESIN COMPOSITION AND CURED PRODUCT OF THE SAME, AND
PRINTED WIRING BOARD
Abstract
A phosphorus-containing oligomer is represented by formula (1):
##STR00001## (R.sup.1 represents a hydrogen atom, an alkyl group
having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon
atoms, or a phenyl group; n is the number of repeating units and an
integer of 1 or more; X is a structural unit represented by
structural formula (x1) or (x2) below; ##STR00002## Y is a hydrogen
atom, a hydroxyl group, or a structural unit represented by the
formula (x1) or (x2); and, in the formula (x1) or (x2), R.sup.2,
R.sup.3, R.sup.4, and R.sup.5 each independently represent a
hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a phenyl
group, or an aralkyl group), wherein the content of components
whose n is 2 or more in the formula (1) is in the range of 5% to
90% in peak area in GPC measurement.
Inventors: |
Hayashi; Koji;
(Ichihara-shi, JP) ; Satou; Yutaka; (Ichihara-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DIC Corporation |
Tokyo |
|
JP |
|
|
Family ID: |
44482805 |
Appl. No.: |
13/932345 |
Filed: |
July 1, 2013 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13579913 |
Oct 26, 2012 |
8512466 |
|
|
PCT/JP2011/051991 |
Feb 1, 2011 |
|
|
|
13932345 |
|
|
|
|
Current U.S.
Class: |
558/76 |
Current CPC
Class: |
Y10T 428/31529 20150401;
C07F 9/306 20130101; C07F 9/657172 20130101; C08G 79/04 20130101;
C07F 9/65746 20130101; Y10T 428/31522 20150401 |
Class at
Publication: |
558/76 |
International
Class: |
C07F 9/6574 20060101
C07F009/6574 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 18, 2010 |
JP |
2010-033449 |
Claims
1-3. (canceled)
4. A method for producing a phosphorus-containing oligomer, the
method comprising mixing a compound (a1) represented by structural
formula (a1-1) or (a1-2) below and a compound (a2) represented by
structural formula (a2) below with each other at a molar ratio of
[compound (a1)/compound (a2)]=0.01/1.0 to 0.99/1.0; causing a
reaction to proceed at 80.degree. C. to 180.degree. C. in the
presence of an acid catalyst; then adding the compound (a1) so that
the total amount on a molar basis is 1.01 to 3.0 times the amount
of the compound (a2) charged; and causing a reaction to proceed at
120.degree. C. to 200.degree. C., ##STR00023## (in the formula,
R.sup.2, R.sup.3, R.sup.4, and R.sup.5 each independently represent
a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a
phenyl group, or an aralkyl group) ##STR00024## (in the formula,
R.sup.1 represents a hydrogen atom, an alkyl group having 1 to 4
carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a
phenyl group).
5-7. (canceled)
Description
TECHNICAL FIELD
[0001] The present invention relates to a phosphorus containing
oligomer that has high solubility in a solvent and exhibits high
flame retardancy and heat resistance in the form of a cured product
thereof, a method for producing the phosphorus-containing oligomer,
a curable resin composition that uses the oligomer as a curing
agent for epoxy resins, a cured product of the curable resin
composition, and a printed wiring board that uses the curable resin
composition.
BACKGROUND ART
[0002] Epoxy resins and epoxy resin compositions containing a
curing agent for epoxy resins as an essential component have
excellent physical properties such as high heat resistance and
moisture resistance and hence are widely used for, for example,
semiconductor sealing materials, electronic components such as
printed circuit boards, the electronic component field, conductive
adhesives such as conductive pastes, other adhesives, matrices for
composite materials, coating materials, photoresist materials, and
development materials.
[0003] In recent years, further enhancement of properties such as
heat resistance, moisture resistance, and solder resistance has
been demanded in such various applications, in particular,
applications to advanced materials. In vehicle-mounted electronic
devices that are particularly required to have high reliability,
the installation position has been changed from a cabin to an
engine compartment having a higher temperature than a cabin. In
addition, reflowing treatment temperature has increased due to use
of lead-free solder. Therefore, high heat resistant materials that
have higher glass transition temperature and can endure a thermal
delamination test (hereinafter, abbreviated as "T288 test") have
been demanded.
[0004] When epoxy resin compositions are used as materials for
printed wiring boards, a flame retardant containing halogen such as
bromine is added together with an antimony compound to impart flame
retardancy to epoxy resin compositions. However, with efforts in
terms of environment and safety in recent years, there has been a
strong demand for the development of an environmentally friendly
and safe method for making compositions have flame retardancy
without using halogen-based flame retardants that may emit dioxins
and without using antimony compounds that may cause cancer. In
addition, in the field of materials for printed wiring boards, use
of halogen-based flame retardants causes degradation of reliability
of printed wiring boards left to stand at high temperature.
Accordingly, halogen-free compositions have been highly
demanded.
[0005] As for an epoxy resin composition that satisfies such
required characteristics and has flame retardancy and heat
resistance, for example, PTL 1 discloses a technique of using, as
an epoxy resin material or a curing agent for epoxy resins, a
phosphorus-containing bisphenol that is obtained as follows:
9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (hereinafter,
abbreviated as "HCA") is allowed to react with
p-hydroxybenzaldehyde and then the reaction product is allowed to
react with phenol.
[0006] However, such a phosphorus-containing bisphenol has
extremely high crystallinity and exhibits almost no solubility in a
solvent. Therefore, such a phosphorus-containing bisphenol cannot
be prepared in the form of varnish for the printed wiring board
materials, and a cured product obtained by using the
phosphorus-containing bisphenol as a curing agent for epoxy resins
does not have satisfactory flame retardancy. In addition, since the
melting point of the phosphorus-containing bisphenol is 200.degree.
C. or more, it is extremely difficult to perform industrial
production.
[0007] NPL 1 discloses a technique of producing an oligomer in THF
from an intermediate product obtained through a reaction between
HCA and p-hydroxybenzaldehyde.
[0008] However, in the technique disclosed in NPL 1, the reaction
product of HCA and p-hydroxybenzaldehyde, which is an intermediate
product, has extremely high crystallinity and thus has low
solubility in a solvent. Therefore, as described in NPL 1, THF,
which is a dangerous solvent having a low flash point, needs to be
used in the subsequent reaction and thus it is impossible to
perform industrial production. In addition, the obtained oligomer
itself has low solubility in a solvent and thus it is difficult to
prepare a varnish for printed wiring board materials.
[0009] Furthermore, PTL 2 discloses a technique of producing a
phosphorus-containing phenolic compound through a reaction between
HCA and hydroxybenzaldehyde. However, the phenolic compound
disclosed in PTL 2 is a monofunctional phenolic compound and thus
has extremely high crystallinity and low solubility in a solvent.
In addition, even when the phenolic compound is used as a curing
agent for epoxy resins, sufficient flame retardancy is not
achieved.
CITATION LIST
Patent Literature
[0010] PTL 1: Japanese Unexamined Patent Application Publication
No. 2004-143166 [0011] PTL 2: Japanese Unexamined Patent.
Application Publication No. 2001-354685
Non Patent Literature
[0011] [0012] NPL 1: "Flame-retardant epoxy resins from novel
phosphorus-containing novolac", polymer (polymer 42 (2001) 3445 to
3454), Ying Ling Liu
SUMMARY OF INVENTION
Technical Problem
[0013] Accordingly, it is an object of the present invention to
provide a phosphorus-containing oligomer that has a significantly
improved solubility in an organic solvent and exhibits high flame
retardancy and heat resistance in the form of a cured product
thereof, a method for producing the phosphorus-containing, oligomer
with high industrial productivity, a curable resin composition
containing the oligomer and a cured product thereof, and a printed
wiring board produced from the composition.
Solution to Problem
[0014] As a result of thorough studies to address the problems
above, the inventors of the present invention have found the
following and have completed the present invention. That is, a
phosphorus-containing oligomer obtained through a reaction between
a phosphorus-containing compound such as HCA and
o-hydroxybenzaldehyde exhibits high solubility in an organic
solvent. Furthermore, when the oligomer is used as a curing agent
for epoxy resins, an epoxy resin material, an additive for
thermosetting resins, or the like and curing is performed, the
cured product exhibits high flame retardancy, has high glass
transition temperature, and can endure a T288 test.
[0015] The present invention relates to a phosphorus-containing
oligomer represented by structural formula (1) below:
##STR00003##
(in the formula, R.sup.1 represents a hydrogen atom, an alkyl group
having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon
atoms, or a phenyl group; n is the number of repeating units and an
integer of 1 or more; X is a structural unit represented by
structural formula (x1) or (x2) below;
##STR00004##
Y is a hydrogen atom, a hydroxyl group, or a structural unit
represented by the structural formula (x1) or (x2); and, in the
structural formula (x1) or (x2), R.sup.2, R.sup.3, R.sup.4, and
R.sup.5 each independently represent a hydrogen atom, an alkyl
group having 1 to 4 carbon atoms, a phenyl group, or an aralkyl
group), wherein the content of components whose n is 2 or more in
the structural formula (1) is in the range of 5% to 90% in terms of
peak area in GPC measurement.
[0016] The present invention also relates to a method for producing
a phosphorus-containing oligomer, the method including mixing a
compound (a1) represented by structural formula (a1-1) or (a1-2)
below and a compound (a2) represented by structural formula (a2)
below with each other at a molar ratio of [compound (a1)/compound
(a2)]=0.01/1.0 to 0.99/1.0; causing a reaction to proceed at
80.degree. C. to 180.degree. C. in the presence of an acid
catalyst; then adding the compound (a1) so that the total amount on
a molar basis is 1.01 to 3.0 times the amount of the compound (a2)
charged; and causing a reaction to proceed at 120.degree. C. to
200.degree. C.,
##STR00005##
(in the formula, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 each
independently represent a hydrogen atom, an alkyl group having 1 to
4 carbon atoms, a phenyl group, or an aralkyl group)
##STR00006##
(in the formula, R.sup.1 represents a hydrogen atom, an alkyl group
having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon
atoms, or a phenyl group).
[0017] The present invention also relates to a curable resin
composition that includes an epoxy resin and a curing agent as
essential components, wherein the phosphorus-containing oligomer is
used as the curing agent.
[0018] The present invention also relates to a cured product
obtained by curing the curable resin composition.
[0019] The present invention also relates to a printed wiring board
obtained by further adding an organic solvent to the curable resin
composition to form a resin composition in the form of varnish,
impregnating a reinforcing base with the resin composition in the
form of varnish, laminating a copper foil on the reinforcing base,
and performing thermocompression bonding.
Advantageous Effects of Invention
[0020] According to the present invention, there can be provided a
phosphorus-containing oligomer that has a significantly improved
solubility in an organic solvent and exhibits high flame retardancy
and heat resistance in the form of a cured product thereof, a
method for producing the phosphorus-containing oligomer with high
industrial productivity, a curable resin composition containing the
oligomer and a cured product thereof, and a printed wiring board
produced from the composition.
BRIEF DESCRIPTION OF DRAWINGS
[0021] FIG. 1 shows a GPC chart of a phosphorus-containing oligomer
(A-1) obtained in Example 1.
[0022] FIG. 2 shows a .sup.13C-NMR chart of the
phosphorus-containing oligomer (A-1) obtained in Example 1.
[0023] FIG. 3 shows an MS spectrum of the phosphorus-containing
oligomer (A-1) obtained in Example 1.
[0024] FIG. 4 shows a GPC chart of a phosphorus-containing oligomer
(A-2) obtained in Example 2.
[0025] FIG. 5 shows a GPC chart of a phosphorus-containing oligomer
(A-3) obtained in Example 3.
[0026] FIG. 6 shows a GPC chart of a phosphorus-containing oligomer
(A-4) obtained in Example 4.
[0027] FIG. 7 shows a GPC chart of a phosphorus-containing oligomer
(A-5) obtained in Example 5.
[0028] FIG. 8 shows a GPC chart of a phenolic compound (A-6)
obtained in Synthetic Comparative Example 1.
[0029] FIG. 9 shows a GPC chart of a phenolic resin (A-7) obtained
in Synthetic Comparative Example 2.
[0030] FIG. 10 shows a GPC chart of a phenolic compound (A-8)
obtained in Synthetic Comparative Example 3.
DESCRIPTION OF EMBODIMENTS
[0031] The present invention will now be described in detail.
[0032] As described above, the phosphorus-containing oligomer of
the present invention is represented by structural formula (1)
below:
##STR00007##
(in the formula, R.sup.1 represents a hydrogen atom, an alkyl group
having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon
atoms, or a phenyl group; n is the number of repeating units and an
integer of 1 or more; X is a structural unit represented by
structural formula (x1) or (x2) below;
##STR00008##
Y is a hydrogen atom, a hydroxyl group, or a structural unit
represented by the structural formula (x1) or (x2); and, in the
structural formula (x1) or (x2), R.sup.2, R.sup.3, R.sup.4, and
R.sup.5 each independently represent a hydrogen atom, an alkyl
group having 1 to 4 carbon atoms, a phenyl group, or an aralkyl
group). The content of components whose n is 2 or more in the
structural formula (1) is in the range of 5% to 90% in terms of
peak area in GPC measurement.
[0033] The phosphorus-containing oligomer includes, as a repeating
unit, a structural unit represented by structural formula (2) below
in the structural formula (1):
##STR00009##
(in the formula, R.sup.1 represents a hydrogen atom, an alkyl group
having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon
atoms, or a phenyl group; n is the number of repeating units and an
integer of 1 or more; and X is a structural unit represented by
structural formula (x1) or (x2) below).
##STR00010##
Therefore, the cured product of the phosphorus-containing oligomer
has high flame retardancy, high glass transition temperature, and
high thermal delamination resistance.
[0034] Specific examples of the structural unit represented by the
structural formula (2) include structural units represented by
structural formulae (2-1) to (2-8) below.
##STR00011## ##STR00012##
[0035] In the present invention, X in the structural formula (1) is
selected from the structural units represented by the structural
formulae (x1) and (x2), but is particularly preferably the
structural unit represented by the structural formula (x1) in view
of flame retardancy. Therefore, among the structural units
represented by the structural formula (2), X is preferably selected
from the structural units represented by the structural formulae
(2-1), (2-2), (2-3), and (2-4) that each correspond to the
structural formula (x-1).
[0036] In the structural formula (1), Y is a hydrogen atom, a
hydroxyl group, or a structural unit represented by the structural
formula (x1) or (x2), but they may be present together in the
phosphorus-containing oligomer. In the present invention, Y is
preferably a hydrogen atom or the structural unit represented by
the structural formula (x1) or (x2) in view of solubility in a
solvent and heat resistance and particularly preferably the
structural unit represented by the structural formula (x1) in view
of flame retardancy.
[0037] As described above, in the phosphorus-containing oligomer,
the content of components whose n is 2 or more in the structural
formula (1) is in the range of 5% to 90% in terms of peak area in
GPC measurement. When the content is in the range, the solubility
of the oligomer in an organic solvent and the flame retardancy of a
cured product are significantly improved.
[0038] Herein, the phrase "the content of components whose n is 2
or more in the structural formula (1)" means a peak area percentage
before 36.0 minutes in a GPC chart measured under the following
conditions.
<GPC Measurement Conditions>
[0039] 4) GPC: the measurement conditions are as follows.
Measurement apparatus: "HLC-8220 GPC" manufactured by Tosoh
Corporation Columns: guard column "HXL-L" manufactured by Tosoh
Corporation, [0040] +"TSK-GEL G2000HXL" manufactured by Tosoh
Corporation, [0041] +"TSK-GEL G2000HXL" manufactured by Tosoh
Corporation, [0042] +"TSK-GEL G3000HXL" manufactured by Tosoh
Corporation, [0043] +"TSK-GEL G4000HXL", manufactured by Tosoh
Corporation Detector: RI (differential refractive refractometer)
Data processing: "GPC-8020 Model II version 4.10" manufactured by
Tosoh Corporation Measurement conditions: column temperature
40.degree. C. [0044] developing solvent tetrahydrofuran [0045] flow
rate 1.0 ml/min Standards: the following monodisperse polystyrenes
whose molecular weights are known were used in accordance with the
measurement manual of the "GPC-8020 Model II version 4.10"
[0046] (Used Polystyrenes)
[0047] "A-500" manufactured by Tosoh Corporation
[0048] "A-1000" manufactured by Tosoh Corporation
[0049] "A-2500" manufactured by Tosoh Corporation
[0050] "A-5000" manufactured by Tosoh Corporation
[0051] "F-1" manufactured by Tosoh Corporation
[0052] "F-2" manufactured by Tosoh Corporation
[0053] "F-4" manufactured by Tosoh Corporation
[0054] "F-10" manufactured by Tosoh Corporation
[0055] "F-20" manufactured by Tosoh Corporation
[0056] "F-40" manufactured by Tosoh Corporation
[0057] "F-80" manufactured by Tosoh Corporation
[0058] "F-128" manufactured by Tosoh Corporation
Samples: solutions (50 .mu.l) obtained by filtrating a 1.0 mass %
tetrahydrofuran solution in terms of resin solid matter through a
micro-filter. 5) NMR: JNM-ECA500 nuclear magnetic resonance
apparatus manufactured by JEOL Ltd. Magnetic field strength: 500
MHz Pulse width: 3.25 .mu.sec Number of acquisitions: 8000
Solvent: DMSO-d6
[0059] Sample concentration: 30 wt % 6) MS: AXIMA-TOF2 manufactured
by SHIMADZU BIOTECH Measurement mode: linear Number of
acquisitions: 50 Sample composition: sample/DHBA/NaTFA/THF=9.4
mg/104.7 mg/6.3 mg/l ml
[0060] In the present invention, when the content of components
whose n is 2 or more is 5% or more in terms of peak area in GPC
measurement, the solubility in a solvent is improved. When the
content is 90% or less, the liquidity in a molten state or the
liquidity in the form of varnish is improved. Herein, the other
component is a component whose n is 1. Thus, in the
phosphorus-containing oligomer of the present invention, the
content of a component whose n is 1 is 95% to 10% in terms of peak
area in GPC measurement. In the present invention, the content of
components whose n is 2 or more is preferably 40% to 75% and the
content of a component whose n is 1 is preferably 60% to 25% to
maintain the solubility in a solvent and the fluidity and to
achieve high heat resistance, in particular, to achieve high glass
transition temperature and high performance in a T288 test.
[0061] More specifically, preferably, the content of a component
whose n is 1 is 95% to 10%, the content of a component whose n is 2
is 3% to 50%, and the content of components whose n is 3 or more is
1% to 45% in view of solubility in a solvent. Particularly
preferably, the content of a component whose n is 1 is 60% to 25%,
the content of a component whose n is 2 is 10% to 45%, and the
content of components whose n is 3 or more is 10% to 40% in view of
good balance of solubility in a solvent, liquidity, and heat
resistance.
[0062] As described above, Y in the structural formula (1) is
preferably a structural unit represented by the structural formula
(x1). Therefore, a phosphorus-containing oligomer in which, in the
structural formula (1), Y is a structural unit represented by the
structural formula (x1), the content of components whose n is 2 or
more is 40% to 75%, and the content of a component whose n is 1 is
60% to 25% is preferably employed in view of flame retardancy and
heat resistance. A phosphorus-containing oligomer in which, in the
structural formula (1), Y is a structural unit represented by the
structural formula (x1), the content of a component whose n is 1 is
95% to 10%, the content of a component whose n is 2 is 3% to 50%,
and the content of components whose n is 3 or more is 1% to 45% is
more preferably employed in view of high flame retardancy, heat
resistance, and solubility in a solvent. A phosphorus-containing
oligomer in which Y is a structural unit represented by the
structural formula (x1), the content of a component whose n is 1 is
60% to 25%, the content of a component whose n is 2 is 10% to 45%,
and the content of components whose n is 3 or more is 10% to 40% is
most preferably employed in view of good balance of flame
retardancy, solubility in a solvent, liquidity, and heat
resistance.
[0063] In the phosphorus-containing oligomer, the content of
phosphorus in the oligomer is preferably 9% to 12% by mass in view
of flame retardancy. The content of phosphorus is measured in
conformity with "JIS K0102 46".
[0064] The phosphorus-containing oligomer described in detail is
preferably a phosphorus-containing oligomer produced by the
following production method of the present invention to achieve
high solubility in an organic solvent and high heat resistance of a
cured product.
[0065] As described above, the production method of the present
invention includes mixing a compound (a1) represented by structural
formula (a1-1) or (a1-2) below and a compound (a2) represented by
structural formula (a2) below with each other at a molar ratio of
[compound (a1)/compound (a2)]=0.01/1.0 to 0.99/1.0; causing a
reaction to proceed at 80.degree. C. to 180.degree. C. in the
presence of an acid catalyst; then adding the compound (a1) so that
the total amount on a molar basis is 1.01 to 3.0 times the amount
of the compound (a2) charged; and causing a reaction to proceed at
120.degree. C. to 200.degree. C.
##STR00013##
(In the formula, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 each
independently represent a hydrogen atom, an alkyl group having 1 to
4 carbon atoms, a phenyl group, or an aralkyl group.)
##STR00014##
(In the formula, R.sup.1 represents a hydrogen atom, an alkyl group
having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon
atoms, or a phenyl group)
[0066] In the present invention, when a phosphorus-containing
oligomer is produced by the method above, the precipitation of a
reaction intermediate can be favorably reduced and higher molecular
weight is easily achieved.
[0067] Examples of the alkyl group having 1 to 5 carbon atoms that
constitutes R.sup.2, R.sup.3, R.sup.4, and R.sup.5 in the
structural formula (a1-1) or (a1-2) include a methyl group, an
ethyl group, an n-propyl group, an i-propyl group, and a t-butyl
group. However, in the compound (a1) used in the present invention,
R.sup.2, R.sup.3, R.sup.4, and R.sup.5 are each preferably a
hydrogen atom in view of flame retardancy. Furthermore, the
compound (a1) is preferably represented by the structural formula
(a1-1) in view of high flame retardancy of a cured product. In the
compound (a2), examples of R.sup.1 in the structural formula (a2)
include a methyl group, an ethyl group, an n-propyl group, and a
methoxy group, but R.sup.1 is preferably a hydrogen atom in view of
the reactivity with the compound (a1) and high flame retardancy of
a cured product.
[0068] Examples of the catalyst that can be used in the method
include inorganic acids such as hydrochloric acid, sulfuric acid,
and phosphoric acid; organic acids such as methanesulfonic acid,
p-toluenesulfonic acid, and oxalic acid; and Lewis acids such as
boron trifluoride, anhydrous aluminum chloride, and zinc chloride.
The amount of such a catalyst used is preferably 0.1% to 5.0% by
mass relative to the total weight of charged raw materials in order
to prevent a decrease in electrical insulation of a cured
product.
[0069] Since the compound (a2) is liquid, the reaction can be
caused to proceed using the compound (a2) as an organic solvent.
However, other organic solvents may be used to improve the work
efficiency or the like. The organic solvent may be a non-ketonic
organic solvent such as an alcohol organic solvent or a hydrocarbon
organic solvent. Specifically, the alcohol organic solvent may be
propylene glycol monomethyl ether and the hydrocarbon organic
solvent may be toluene or xylene.
[0070] After the reaction, an intended product can be obtained by
performing drying under reduced pressure.
[0071] The curable resin composition of the present invention is a
curable resin composition including an epoxy resin and a curing
agent as essential components, and the phosphorus-containing
oligomer of the present invention is used as the curing agent.
[0072] The epoxy resin used herein may be various epoxy resins.
Examples of the epoxy resin include bisphenol epoxy resins such as
a bisphenol A epoxy resin and a bisphenol F epoxy resin; biphenyl
epoxy resins such as a biphenyl epoxy resin and a tetramethyl
biphenyl epoxy resin; novolac epoxy resins such as a phenolic
novolac epoxy resin, a cresol novolac epoxy resin, a bisphenol A
novolac epoxy resin, epoxidized condensates derived from a phenol
and an aromatic aldehyde having a phenolic hydroxyl group, and a
biphenyl novolac epoxy resin; triphenylmethane epoxy resins;
tetraphenylethane epoxy resins; dicyclopentadiene-phenol addition
reaction epoxy resins; phenol aralkyl epoxy resins; epoxy resins
intramolecularly having a naphthalene skeleton, such as a naphthol
novolac epoxy resin, a naphthol aralkyl epoxy resin, a
naphthol-phenol cocondensation novolac epoxy resin, a
naphthol-cresol cocondensation novolac epoxy resin,
diglycidyloxynaphthalene, and
1,1-bis(2,7-diglycidyloxy-1-naphthyl)alkane; and
phosphorus-containing epoxy resins. These epoxy resins may be used
alone or in combination of two or more thereof.
[0073] Examples of the phosphorus-containing epoxy resin include
epoxidized products of a phenolic resin obtained through a reaction
between 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide
(hereinafter, abbreviated as "HCA") and a quinone, epoxy resins
obtained by modifying a phenolic novolac epoxy resin with HCA,
epoxy resins obtained by modifying a cresol novolac epoxy resin
with HCA, epoxy resins obtained by modifying a bisphenol A epoxy
resin with a phenolic resin obtained through a reaction between HCA
and a quinone, and epoxy resins obtained by modifying a bisphenol F
epoxy resin with a phenolic resin obtained through a reaction
between HCA and a quinone.
[0074] Among the above-described epoxy resins, novolac epoxy resins
and epoxy resins having a naphthalene skeleton in the molecular
structure are particularly preferred in view of heat resistance;
and bisphenol epoxy resins and novolac epoxy resins are preferred
in view of solubility in a solvent.
[0075] The amounts of the epoxy resin and the phosphorus-containing
oligomer in the curable resin composition of the present invention
are not particularly limited. The amounts are preferably set such
that the amount of active hydrogen in the phosphorus-containing
oligomer is 0.7 to 1.5 equivalents per equivalent of epoxy groups
in total of the epoxy resin because a cured product to be obtained
has good characteristics.
[0076] In the curable resin: composition of the present invention,
a curing agent other than the phosphorus-containing oligomer may be
used as the curing agent for epoxy resins so long as the advantages
of the present invention are not impaired. Such another curing
agent may be an amine compound, an amide compound, an acid
anhydride compound, a phenolic compound, or the like. Specific
examples of the amine compound include diaminodiphenylmethane,
diethylenetriamine, triethylenetetramine, diaminodiphenyl sulfone,
isophoronediamine, imidazole, BF.sub.3-amine complexes, and
guanidine derivatives. Specific examples of the amide compound
include dicyandiamide and polyamide resins synthesized from a dimer
of linolenic acid and ethylenediamine. Specific examples of the
acid anhydride compound include phthalic anhydride, trimellitic
anhydride, pyromellitic dianhydride, maleic anhydride,
tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride,
methylnadic anhydride, hexahydrophthalic anhydride, and
methylhexahydrophthalic anhydride. Specific examples of the
phenolic compound include polyhydric phenolic compounds such as a
phenolic novolac resin, a cresol novolac resin, an aromatic
hydrocarbon formaldehyde resin-modified phenolic resin, a
dicyclopentadiene-phenol adduct resin, a phenol aralkyl resin
(Xylok resin), naphthol aralkyl resin, a trisphenylolmethane resin,
a tetraphenylolethane resin, a naphthol novolac resin, a
naphthol-phenol cocondensation novolac resin, a naphthol-cresol
cocondensation novolac resin, a biphenyl-modified phenolic resin (a
polyhydric phenolic compound in which phenolic nuclei are bonded to
each other through bismethylene groups), a biphenyl-modified
naphthol resin (a polyhydric naphthol compound in which phenolic
nuclei are bonded to each other through bismethylene groups), an
aminotriazine-modified phenolic resin (a compound intramolecularly
having a phenolic skeleton, a triazine ring, and a primary amino
group), and an alkoxy-group-containing aromatic ring modified
novolac resin (a polyhydric phenolic compound in which phenolic
nuclei and alkoxy-group-containing aromatic rings are bonded to
each other through formaldehyde).
[0077] Among these compounds, compounds intramolecularly having a
large number of aromatic skeletons are particularly preferred in
view of excellent low thermal expansion of a cured product.
Specifically, in view of excellent low thermal expansion, preferred
examples of the compounds include a phenolic novolac resin, a
cresol novolac resin, an aromatic hydrocarbon formaldehyde
resin-modified phenolic resin, a phenol aralkyl resin, a naphthol
aralkyl resin, a naphthol novolac resin, a naphthol-phenol
cocondensation novolac resin, a naphthol-cresol cocondensation
novolac resin, a biphenyl-modified phenolic resin, a
biphenyl-modified naphthol resin, an aminotriazine-modified
phenolic resin, and an alkoxy-group-containing aromatic ring
modified novolac resin (a polyhydric phenolic compound in which
phenolic nuclei and alkoxy-group-containing aromatic rings are
bonded to each other through formaldehyde).
[0078] As for the aminotriazine-modified phenolic resin, that is, a
compound intramolecularly having a phenolic skeleton, a triazine
ring, and a primary amino group, a compound having a molecular
structure obtained by condensation reaction between a triazine
compound, a phenol, and an aldehyde is preferred because a cured
product has high flame retardancy.
[0079] In view of the flame retardancy of a cured product, the
other curing agent described above is preferably used such that the
content of phosphorus in the solid matter of the curable resin
composition according to the present invention is 1% to 9%.
[0080] If necessary, the curable resin composition of the present
invention may also appropriately contain a curing accelerator.
Various curing accelerators can be used as the curing accelerator.
Examples of the curing accelerator include phosphorus compounds,
tertiary amines, imidazole, metal salts of organic acids, Lewis
acids, and amine complex salts. In particular, when the curable
resin composition is used as a semiconductor sealing material, a
preferred phosphorus compound is triphenyl phosphine and a
preferred amine compound is 2-ethyl-4-methylimidazole in view of
excellent curing properties, heat resistance, electric
characteristics, moisture resistance reliability, and the like. The
amount of the curing accelerator used is preferably 0.01% to 1% by
mass in the curable resin composition.
[0081] As described above, the curable resin composition of the
present invention having been described so far in detail exhibits
high solubility in a solvent. Therefore, the curable resin
composition preferably contains, in addition to the above-described
components, an organic solvent. Examples of the organic solvent
that can be used include methyl ethyl ketone, acetone,
dimethylformamide, methyl isobutyl ketone, methoxy propanol,
cyclohexanone, methyl cellosolve, ethyl diglycol acetate, and
propylene glycol monomethyl ether acetate. The selection of the
solvent and the appropriate amount of the solvent used can be
appropriately determined on the basis of the application. For
example, in applications to printed wiring boards, alcohol organic
solvents or carbonyl group-containing organic solvents having a
boiling point of 160.degree. C. or less, such as methyl ethyl
ketone, acetone, and 1-methoxy-2-propanol are preferred and such
organic solvents are preferably used such that a nonvolatile
content is 40% to 80% by mass. In applications to adhesive films
for build-up, the organic solvent is preferably a ketone such as
acetone, methyl ethyl ketone, or cyclohexanone; an acetate such as
ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol
monomethyl ether acetate, or carbitol acetate; a carbitol such as
cellosolve or butyl carbitol; an aromatic hydrocarbon such as
toluene or xylene; or dimethylformamide, dimethylacetamide,
N-methylpyrrolidone, or the like. In addition, the organic solvent
is preferably used such that a nonvolatile content is 30% to 60% by
mass.
[0082] To achieve flame retardancy, the curable resin composition
may contain a non-halogen flame retardant that substantially
contains no halogen atoms in the field of, for example, printed
wiring boards as long as reliability is not degraded.
[0083] Examples of the non-halogen flame retardant include
phosphorus flame retardants, nitrogen flame retardants, silicone
flame retardants, inorganic flame retardants, and organic metal
salt flame retardants. Use of these flame retardants is not limited
at all. The flame retardants may be used alone, in combination of
flame retardants of the same type, or in combination of flame
retardants of different types.
[0084] Inorganic and organic flame retardants can be used as the
phosphorus flame retardants. Examples of such inorganic compounds
include red phosphorus and inorganic nitrogen-containing phosphorus
compounds such as ammonium phosphates (e.g., monoammonium
phosphate, diammonium phosphate, triammonium phosphate, and
ammonium polyphosphate) and phosphoric acid amide.
[0085] The red phosphorus is preferably surface-treated in order to
prevent hydrolysis and the like. Examples of such a surface
treatment method include (i) a method of forming a coating with an
inorganic compound such as magnesium hydroxide, aluminum hydroxide,
zinc hydroxide, titanium hydroxide, bismuth oxide, bismuth
hydroxide, bismuth nitrate, or a mixture of the foregoing; (ii) a
method of forming a coating with a mixture of an inorganic compound
such as magnesium hydroxide, aluminum hydroxide, zinc hydroxide, or
titanium hydroxide, and a thermosetting resin such as a phenolic
resin; and (iii) a method of forming a coating with a thermosetting
resin such as a phenolic resin on a coating made of an inorganic
compound such as magnesium hydroxide, aluminum hydroxide, zinc
hydroxide, or titanium hydroxide to provide double coatings.
[0086] Examples of the organic phosphorus compounds include, in
addition to general-purpose organic phosphorus compounds such as
phosphoric acid ester compounds, phosphonic acid compounds,
phosphinic acid compounds, phosphine oxide compounds, phosphorane
compounds, and organic nitrogen-containing phosphorus compounds,
cyclic organic phosphorus compounds such as
9,10-dihydro-9-oxa-10-phosphaphenanthrene=10-oxide,
10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene=10-oxide,
and
10-(2,7-dihydroxynaphthyl)-10H-9-oxa-10-phosphaphenanthrene=10-oxide,
and derivatives obtained by reactions between the cyclic organic
phosphorus compounds and compounds such as epoxy resins and
phenolic resins.
[0087] The amount of a phosphorus flame retardant added is
appropriately selected on the basis of the type of the phosphorus
flame retardant, other components in the curable resin composition,
and a desired degree of flame retardancy. For example, in 100 parts
by mass of a curable resin composition containing all components
such as an epoxy resin, a curing agent, a non-halogen flame
retardant, a filler, and other additives, when red phosphorus is
used as a non-halogen flame retardant, red phosphorus is preferably
added in the range of 0.1 to 2.0 parts by mass. Similarly, when an
organic phosphorus compound is used, the organic phosphorus
compound is preferably added in the range of 0.1 to 10.0 parts by
mass, particularly preferably, in the range of 0.5 to 6.0 parts by
mass.
[0088] When the phosphorus flame retardant is used, the phosphorus
flame retardant may be used together with hydrotalcite, magnesium
hydroxide, boride compounds, zirconium oxide, black dyes, calcium
carbonate, zeolite, zinc molybdate, activated carbon, or the
like.
[0089] Examples of the nitrogen flame retardants include triazine
compounds, cyanuric acid compounds, isocyanuric acid compounds, and
phenothiazine. Triazine compounds, cyanuric acid compounds, and
isocyanuric acid compounds are preferred.
[0090] Examples of the triazine compounds include melamine,
acetoguanamine, benzoguanamine, melon, melam, succinoguanamine,
ethylenedimelamine, melamine polyphosphate, and triguanamine;
aminotriazine sulfate compounds such as guanylmelamine sulfate,
melem sulfate, and melam sulfate; the above-described
aminotriazine-modified phenolic resin; and compounds obtained by
further modifying the aminotriazine-modified phenolic resin with
tung oil, isomerized linseed oil, or the like.
[0091] Specific examples of the cyanuric acid compounds include
cyanuric acid and melamine cyanurate.
[0092] The amount of such a nitrogen flame retardant added is
appropriately selected on the basis of the type of the nitrogen
flame retardant, other components in the curable resin composition,
and a desired degree of flame retardancy. For example, in 100 parts
by mass of a curable resin composition containing all components
such as an epoxy resin, a curing agent, a non-halogen flame
retardant, a filler, and other additives, the nitrogen flame
retardant is preferably added in the range of 0.05 to 10 parts by
mass, particularly preferably, in the range of 0.1 to 5 parts by
mass.
[0093] Such a nitrogen flame retardant may be used together with a
metal hydroxide, a molybdenum compound, or the like.
[0094] The silicone flame retardants are not particularly limited
as long as the silicone flame retardants are organic compounds
having silicon atoms. Examples of the silicone flame retardants
include silicone oil, silicone rubber, and silicone resin.
[0095] The amount of such a silicone flame retardant added is
appropriately selected on the basis of the type of the silicone
flame retardant, other components in the curable resin composition,
and a desired degree of flame retardancy. For example, in 100 parts
by mass of a curable resin composition containing all components
such as an epoxy resin, a curing agent, a non-halogen flame
retardant, a filler, and other additives, the silicone flame
retardant is preferably added in the range of 0.05 to 20 parts by
mass. Such a silicone flame retardant may be used together with a
molybdenum compound, alumina, or the like.
[0096] Examples of the inorganic flame retardants include metal
hydroxides, metal oxides, metal carbonate compounds, metal powders,
boron compounds, and low-melting glass.
[0097] Specific examples of the metal hydroxides include aluminum
hydroxide, magnesium hydroxide, dolomite, hydrotalcite, calcium
hydroxide, barium hydroxide, and zirconium hydroxide.
[0098] Specific examples of the metal oxides include zinc
molybdate, molybdenum trioxide, zinc stannate, tin oxide, aluminum
oxide, iron oxide, titanium oxide, manganese oxide, zirconium
oxide, zinc oxide, molybdenum oxide, cobalt oxide, bismuth oxide,
chromium oxide, nickel oxide, copper oxide, and tungsten oxide.
[0099] Specific examples of the metal carbonate compounds include
zinc carbonate, magnesium carbonate, calcium carbonate, barium
carbonate, basic magnesium carbonate, aluminum carbonate, iron
carbonate, cobalt carbonate, and titanium carbonate.
[0100] Specific examples of the metal powders include powders of
aluminum, iron, titanium, manganese, zinc, molybdenum, cobalt,
bismuth, chromium, nickel, copper, tungsten, and tin.
[0101] Specific examples of the boron compounds include zinc
borate, zinc metaborate, barium metaborate, boric acid, and
borax.
[0102] Specific examples of the low-melting glass include CEEPREE
(Bokusui Brown Co., Ltd.), hydrated glass SiO.sub.2--MgO--H.sub.2O,
and glassy compounds of PbO--B.sub.2O.sub.3,
ZnO-P.sub.2O.sub.5--MgO, P.sub.2O.sub.5--B.sub.2O.sub.3--PbO--MgO,
P--Sn--O--F, PbO-V.sub.2O.sub.5--TeO.sub.2,
Al.sub.2O.sub.3--H.sub.2O, and lead borosilicate.
[0103] The amount of such an inorganic flame retardant added is
appropriately selected on the basis of the type of the inorganic
flame retardant, other components in the curable resin composition,
and a desired degree of flame retardancy. For example, in 100 parts
by mass of a curable resin composition containing all components
such as an epoxy resin, a curing agent, a non-halogen flame
retardant, a filler, and other additives, the inorganic flame
retardant is preferably added in the range of 0.05 to 20 parts by
mass, particularly preferably, in the range of 0.5 to 15 parts by
mass.
[0104] Examples of the organic metal salt flame retardants include
ferrocene, acetylacetonato metal complexes, organic metal carbonyl
compounds, organic cobalt salt compounds, organic metal sulfonates,
and compounds in which metal atoms and aromatic compounds or
heterocyclic compounds are bonded to each other through ionic bonds
or coordinate bonds.
[0105] The amount of such an organic metal salt flame retardant
added is appropriately selected on the basis of the type of the
organic metal salt flame retardant, other components in the curable
resin composition, and a desired degree of flame retardancy. For
example, in 100 parts by mass of a curable resin composition
containing all components such as an epoxy resin, a curing agent, a
non-halogen flame retardant, a filler, and other additives; the
organic metal salt flame retardant is preferably added in the range
of 0.005 to 10 parts by mass.
[0106] The curable resin composition of the present invention may
optionally contain an inorganic filler. Examples of the inorganic
filler include fused silica, crystalline silica, alumina, silicon
nitride, and aluminum hydroxide. When the amount of such an
inorganic filler added is made particularly large, fused silica is
preferably used. The fused silica may be used in the form of
fragments or spheres. To increase the amount of fused silica added
and to suppress an increase in the melt viscosity of the
composition, fused silica in the form of spheres is preferably
mainly used. To increase the amount of spherical silica added, the
size distribution of silica particles is preferably appropriately
adjusted. The filling factor of the filler is preferably high in
view of flame retardancy and particularly preferably 20% by mass or
more relative to the whole amount of the curable resin composition.
In applications to conductive paste and the like, a conductive
filler such as silver powder or copper powder may be used.
[0107] The curable resin composition of the present invention may
optionally contain various additives such as a silane coupling
agent, a release agent, a pigment, and an emulsifying agent.
[0108] The curable resin composition of the present invention can
be obtained by uniformly mixing the components above. The curable
resin composition can be easily cured by a method similar to known
methods. Examples of such a cured product include formed cured
products such as multilayer products, cast products, adhesive
layers, coatings, and films.
[0109] Examples of applications of the curable resin composition
according to the present invention include printed wiring board
materials, resin compositions for flexible wiring boards,
interlayer insulating materials for build-up boards, semiconductor
sealing materials, conductive pastes, adhesive films for build-up,
resin casting materials, and adhesives.
[0110] Among these various applications, in the applications to
insulating materials for printed wiring boards and electronic
circuit boards and adhesive films for build-up, the curable resin
composition can be used as insulating materials for boards within
which passive components such as capacitors and active components
such as IC chips are embedded, so-called electronic-component
built-in boards.
[0111] Among these, the curable resin composition has
characteristics of high flame retardancy, high heat resistance, and
solubility in a solvent and hence is preferably used for printed
wiring board materials, resin compositions for flexible wiring
boards, and interlayer insulating materials for build-up boards.
The curable resin composition is particularly preferably used for
printed circuit boards.
[0112] A printed circuit board of the present invention can be
produced from the curable resin composition of the present
invention by a method in which a curable resin composition that is
in the form of varnish and contains an epoxy resin, a
phosphorus-containing oligomer, and furthermore an organic solvent
is impregnated into a reinforcing base; a copper foil is laminated
on the reinforcing base; and the resultant laminate is subjected to
thermocompression bonding. Examples of the reinforcing base that
can be used herein include paper, glass cloth, glass nonwoven
fabric, aramid paper, aramid cloth, glass mat, and glass roving
cloth. Such a method will be further described in detail. The
curable resin composition in the form of varnish is heated to a
heating temperature according to the type of a solvent used,
preferably to 50.degree. C. to 170.degree. C., to provide a prepreg
that is a cured product. The mass ratio of the resin composition
and the reinforcing base that are used herein is not particularly
limited, but the mass ratio is generally preferably adjusted such
that the resin content in the prepreg is 20% to 60% by mass. The
thus-obtained prepreg is then stacked by a standard method, a
copper foil is appropriately laminated thereon, and the resultant
laminate is subjected to thermocompression bonding under a pressure
of 1 to 10 MPa at 170.degree. C. to 250.degree. C. for 10 minutes
to 3 hours, whereby an intended printed circuit board can be
provided.
[0113] A flexible wiring board is produced from the curable resin
composition of the present invention as follows. The
phosphorus-containing oligomer, an epoxy resin, and an organic
solvent and optionally another curing agent and a curing
accelerator are mixed with each other and applied onto an
electrical insulating film with a coater such as a reverse roll
coater or a comma coater. The electrical insulating film is then
heated with a heater at 60.degree. C. to 170.degree. C. for 1 to 15
minutes to evaporate the solvent, whereby the adhesive composition
is brought into the B-stage. A metal foil is then bonded to the
adhesive by thermocompression bonding with a heating roll or the
like. At this time, the compression bonding pressure is preferably
2 to 200 N/cm and the compression bonding temperature is preferably
40.degree. C. to 200.degree. C. When sufficient bonding properties
are achieved at this time, this procedure may be finished. When
complete curing is required, postcure is preferably further
performed at 100.degree. C. to 200.degree. C. for 1 to 24 hours.
The adhesive composition film finally cured preferably has a
thickness in the range of 5 to 100 .mu.m.
[0114] An interlayer insulating material for build-up boards is
produced from the curable resin composition of the present
invention by, for example, the following method. The curable resin
composition appropriately containing rubber, a filler, and the like
is applied onto a wiring board in which circuits have been formed
by a spray coating method, a curtain coating method, or the like
and is subsequently cured. Holes are then optionally made in
predetermined through-hole portions and the like. The board is
treated with a roughening agent and the surface thereof is rinsed
with hot water to form irregularities. The board is plated with a
metal such as copper. The plating method is preferably electroless
plating or electrolytic plating. Examples of the roughening agent
include an oxidizing agent, an alkali, and an organic solvent. Such
a procedure is sequentially repeated as needed to alternately build
up a resin insulating layer and a conductor layer having a
predetermined circuit pattern. As a result, a build-up board can be
provided. Note that holes are made in the through-hole portions
after the formation of a resin insulating layer serving as an
outermost layer. Alternatively, a build-up board can be produced
without the plating process as follows: a copper foil with a resin
in which the resin composition has' been semi-cured on the copper
foil is bonded to a wiring board in which circuits have been formed
by thermocompression bonding at 170.degree. C. to 250.degree. C.,
whereby a roughened surface is formed.
[0115] An adhesive film for build-up is produced from the curable
resin composition of the present invention by, for example, a
method in which the curable resin composition of the present
invention is applied onto a support film to form a resin
composition layer, whereby an adhesive film for multilayer printed
wiring boards is provided.
[0116] When the curable resin composition of the present invention
is used for an adhesive film for build-up, it is important that the
adhesive film softens under a lamination temperature condition
(generally 70.degree. C. to 140.degree. C.) in a vacuum lamination
method and exhibits liquidity (resin flow) with which via holes or
through-holes in a circuit board can be filled with the resin at
the same time as lamination of the circuit board. The
above-described components are preferably mixed with each other so
that such characteristics are exhibited.
[0117] Herein, through-holes in multilayer printed wiring boards
generally have a diameter of 0.1 to 0.5 mm and a depth of 0.1 to
1.2 mm, and it is preferable that through-holes satisfying these
ranges can be filled with the resin. Note that, when lamination is
performed on both surfaces of a circuit board, through-holes are
desirably filled to about half of the through-holes.
[0118] Specifically, the above-described method for producing an
adhesive film can be performed as follows. The curable resin
composition in the form of varnish according to the present
invention is prepared. The varnish composition is then applied onto
a surface of a support film and the organic solvent is subsequently
removed by heating, hot-air blowing, or the like to form a layer
(a) of the curable resin composition.
[0119] The formed layer (a) generally has a thickness equal to or
larger than the thickness of a conductor layer. Since a circuit
board generally has a conductor layer with a thickness in the range
of 5 to 70 .mu.m, the resin composition layer preferably has a
thickness of 10 to 100 .mu.m.
[0120] Note that the layer (a) may be covered with a protective
film described below. By protecting the surface of the resin
composition layer with a protective film, adhesion of dust or the
like to the surface and scratching formed on the surface can be
prevented.
[0121] The support film and the protective film may be composed of,
for example, a polyolefin such as polyethylene, polypropylene, or
polyvinyl chloride; a polyester such as polyethylene terephthalate
(hereinafter, sometimes abbreviated as "PET") or polyethylene
naphthalate; polycarbonate; polyimide; release paper; or a metal
foil such as copper foil or aluminum foil. Note that the support
film and the protective film may be subjected to a mat treatment, a
corona treatment, and a release treatment.
[0122] The thickness of the support film is not particularly
limited and is generally 10 to 150 .mu.m and preferably 25 to 50
.mu.m. The thickness of the protective film is preferably 1 to 40
.mu.m.
[0123] The above-described support film is detached after the
lamination is performed on a circuit board or after an insulating
layer is formed by heat-curing. By detaching the support film after
the adhesion film is heat-cured, adhesion of dust or the like in
the curing step can be prevented. When the support film is detached
after the curing, the support film is generally subjected to a
release treatment in advance.
[0124] A method for producing a multilayer printed wiring board
with the thus-obtained adhesive film is performed by, for example,
in the case where the layer (a) is protected with a protective
film, removing the protective film and performing lamination such
that the layer (a) is in direct contact with a single surface or
both surfaces of a circuit board by, for example, a vacuum
lamination method. The lamination may be performed by a batch
process or a continuous process with rolls. The adhesive film and
the circuit board may be optionally heated (preheated) before the
lamination.
[0125] As for the lamination conditions, lamination is preferably
performed at a compression bonding temperature (lamination
temperature) of 70.degree. C. to 140.degree. C., at a compression
bonding pressure of 1 to 11 kgf/cm.sup.2 (9.8.times.10.sup.4 to
107.9.times.10.sup.4 N/m.sup.2), and under a reduced air pressure
of 20 mmHg (26.7 hPa) or less.
[0126] When the curable resin composition of the present invention
is used as a conductive paste, for example, there are a method in
which fine conductive particles are dispersed in the curable resin
composition to provide a composition for an anisotropic conductive
film and a method in which the curable resin composition is turned
into a resin composition paste for circuit connection or an
anisotropic conductive adhesive, the resin composition paste and
the anisotropic conductive adhesive being in a liquid state at room
temperature.
[0127] In the preparation of a semiconductor sealing material from
the curable resin composition of the present invention, an epoxy
resin composition prepared for semiconductor sealing materials can
be produced by sufficiently melt-mixing the epoxy resin, the
phosphorus-containing oligomer, the curing accelerator, and
optionally another epoxy resin curing agent, and additives such as
an inorganic filler optionally using an extruder, a kneader, a
roll, or the like until uniform mixing is achieved. At this time,
the inorganic filler is generally silica. The filling factor of the
inorganic filler is preferably in the range of 30% to 95% by mass
relative to 100 parts by mass of the epoxy resin composition;
particularly preferably 70 parts by mass or more to improve flame
retardancy, moisture resistance, and resistance to solder cracking
and to decrease linear expansion coefficient; and more preferably
80 parts by mass or more to considerably improve the advantages. As
for semiconductor package forming, there is a method in which the
composition is formed by casting or with a transfer molding
apparatus, an injection molding apparatus, or the like and then
heated at 50.degree. C. to 200.degree. C. for 2 to 10 hours to
provide formed products serving as semiconductor devices.
[0128] The method for providing the cured product of the present
invention may be performed in conformity with a typical method for
curing a curable resin composition. For example, the heating
temperature may be appropriately selected in accordance with the
types of curing agents combined or the applications. In general,
the composition obtained by the above method may be heated at about
20.degree. C. to 250.degree. C.
[0129] Accordingly, by using the phosphorus-containing oligomer,
the solubility in a solvent is considerably improved compared with
existing phosphorus-modified phenolic resins; and, in the form of a
cured product, flame retardancy, heat resistance, and heat
resistance reliability can be exhibited and applications to the
most advanced printed wiring board materials can be achieved. In
addition, the phenolic resin can be efficiently and readily
produced by the production method of the present invention and
molecular design according to the degree of the intended properties
can be performed.
EXAMPLES
[0130] The present invention will now be specifically described
based on Examples and Comparative Examples. Note that melt
viscosity at 180.degree. C., softening point, the content of
phosphorus, GPC measurement, NMR, and MS spectrum were measured
under the following conditions.
1) Melt viscosity at 180.degree. C.: conformity with ASTM D4287 2)
Softening-point measurement method: JIS K7234 3) Method for
measuring the content of phosphorus: conformity with JIS K0102-46
4) GPC: the measurement conditions are as follows.
[0131] Measurement apparatus: "HLC-8220 GPC" manufactured by Tosoh
Corporation
Columns: guard column "HXL-L" manufactured by Tosoh Corporation,
[0132] +"TSK-GEL G2000HXL" manufactured by Tosoh Corporation,
[0133] +"TSK-GEL G2000HXL" manufactured by Tosoh Corporation,
[0134] +"TSK-GEL G3000HXL" manufactured by Tosoh Corporation,
[0135] +"TSK-GEL G4000HXL", manufactured by Tosoh Corporation
Detector: RI (differential refractive refractometer) Data
processing: "GPC-8020 Model II version 4.10" manufactured by Tosoh
Corporation Measurement conditions: column temperature 40.degree.
C. [0136] developing solvent tetrahydrofuran [0137] flow rate 1.0
ml/min Standards: the following monodisperse polystyrenes whose
molecular weights are known were used in accordance with the
measurement manual of the "GPC-8020 Model II version 4.10"
[0138] (Used Polystyrenes)
[0139] "A-500" manufactured by Tosoh Corporation
[0140] "A-1000" manufactured by Tosoh Corporation
[0141] "A-2500" manufactured by Tosoh Corporation
[0142] "A-5000" manufactured by Tosoh Corporation
[0143] "F-1" manufactured by Tosoh Corporation
[0144] "F-2" manufactured by Tosoh Corporation
[0145] "F-4" manufactured by Tosoh Corporation
[0146] "F-10" manufactured by Tosoh Corporation
[0147] "F-20" manufactured by Tosoh Corporation
[0148] "F-40" manufactured by Tosoh Corporation
[0149] "F-80" manufactured by Tosoh Corporation
[0150] "F-128" manufactured by Tosoh Corporation
Samples: solutions (50 .mu.l) obtained by filtrating a 1.0 mass %
tetrahydrofuran solution in terms of resin solid matter through a
micro-filter. 5) NMR: JNM-ECA500 nuclear magnetic resonance
apparatus manufactured by JEOL Ltd. Magnetic field strength: 500
MHz Pulse width: 3.25 .mu.sec Number of acquisitions: 8000
Solvent: DMSO-d6
[0151] Sample concentration: 30 mass % 6) MS: AXIMA-TOF2
manufactured by SHIMADZU BIOTECH Measurement mode: linear Number of
acquisitions: 50 Sample composition: sample/DHBA/NaTFA/THF=9.4
mg/104.7 mg/6.3 mg/l ml
[0152] The content of components whose number of repeating units in
the structural formula (1) is 2 or more (hereinafter abbreviated as
n=2 or more) was calculated based on a peak area before 36.0
minutes in a GPC chart.
Example 1
Synthesis of Phosphorus-Containing Oligomer (A-1)
[0153] A flask equipped with a thermometer, a cooling tube, a
fractional distillation column, a nitrogen-gas inlet tube, and a
stirrer was charged with 122 g (1.0 mol) of 2-hydroxybenzaldehyde,
151.2 g (0.7 mol) of
9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (hereinafter,
abbreviated as "HCA"), and 2.23 g (0.019 mol) of oxalic acid. The
mixture was heated to 120.degree. C. to allow the reaction to
proceed for one hour: Subsequently, 172.8 g (0.8 mol) of HCA was
added to the flask, and the mixture was heated to 180.degree. C. to
allow the reaction to proceed for three hours. Water was then
removed under heating and reduced pressure to obtain 410 g of a
phosphorus-containing oligomer (A-1) having a structural unit
represented by structural formula below.
##STR00015##
The obtained phosphorus-containing oligomer had a softening point
of 138.degree. C. (B&R method), a melt viscosity (measurement
method: ICI viscometer method, measurement temperature: 180.degree.
C.) of 66 dPas, a hydroxyl equivalent of 428 g/eq, and a phosphorus
content of 10.5%. The content of a component whose n=1 was 51%, the
content of a component whose n=2 was 29.6%, and the content of
components whose n=3 or more was 19.4% (the content of components
whose n=2 or more was 49.0%). FIG. 1 shows a GPC chart of the
obtained phosphorus-containing oligomer. FIG. 2 shows a
.sup.13C-NMR chart of the obtained phosphorus-containing oligomer.
FIG. 3 shows an MS spectrum of the obtained phosphorus-containing
oligomer.
Example 2
Synthesis of Phosphorus-Containing Oligomer (A-2)
[0154] A flask equipped with a thermometer, a cooling tube,
fractional distillation column, a nitrogen-gas inlet tube, and a
stirrer was charged with 122 g (1.0 mol) of o-hydroxybenzaldehyde,
108 g (0.5 mol) of HCA, and 2.23 g (0.019 mol) of oxalic acid. The
mixture was heated to 120.degree. C. to allow the reaction to
proceed for one hour. Subsequently, 216 g (1.0 mol) of HCA was
added to the flask, and the mixture was heated to 180.degree. C. to
allow the reaction to proceed for three hours. Water was then
removed under heating and reduced pressure to obtain 415 g of a
phosphorus-containing oligomer (A-2) having a structural unit
represented by structural formula below.
##STR00016##
The obtained phosphorus-containing oligomer had a softening point
of 130.degree. C. (B&R method), a melt viscosity (measurement
method: ICI viscometer method, measurement temperature: 180.degree.
C.) of 72 dPas, a hydroxyl equivalent of 430 g/eq, and a phosphorus
content of 10.5 mass %. The content of a component whose n=1 was
55.3%, the content of a component whose n=2 was 26.0%, and the
content of components whose n=3 or more was 18.7% (the content of
components whose n=2 or more was 44.7%). FIG. 4 shows a GPC chart
of the obtained phenolic resin.
Example 3
Synthesis of Phosphorus-Containing Oligomer (A-3)
[0155] A flask equipped with a thermometer, a cooling tube, a
fractional distillation column, a nitrogen-gas inlet tube, and a
stirrer was charged with 122 g (1.0 mol) of o-hydroxybenzaldehyde,
129.6 g (0.6 mol) of HCA, and 3.81 g (0.032 mol) of oxalic acid.
The mixture was heated to 120.degree. C. to allow the reaction to
proceed for one hour. Subsequently, 129.6 g (0.6 mol) of HCA was
added to the flask, and the mixture was heated to 180.degree. C. to
allow the reaction to proceed for three hours. Water was then
removed under heating and reduced pressure to obtain 415 g of a
phosphorus-containing oligomer (A-3) having a structural unit
represented by structural formula below.
##STR00017##
The obtained phosphorus-containing oligomer had a softening point
of 150.degree. C. (B&R method), a melt viscosity (measurement
method: ICI viscometer method, measurement temperature: 180.degree.
C.) of 105 dPas, a hydroxyl equivalent of 363.2 g/eq, and a
phosphorus content of 9.9 mass %. The content of a component whose
n=1 was 33.8%, the content of a component whose n=2 was 31.2%, and
the content of components whose n=3 or more was 35.0% (the content
of components whose n=2 or more was 66.2%). FIG. 5 shows a GPC
chart of the obtained phenolic resin.
Example 4
Synthesis of Phenolic Resin (A-4)
[0156] A flask equipped with a thermometer, a cooling tube, a
fractional distillation column, a nitrogen-gas inlet tube, and a
stirrer was charged with 122 g (1.0 mol) of o-hydroxybenzaldehyde,
129.6 g (0.6 mol) of HCA, and 5.54 g (0.047 mol) of oxalic acid.
The mixture was heated to 120.degree. C. to allow the reaction to
proceed for two hours. Subsequently, 129.6 g (0.6 mol) of HCA was
added to the flask, and the mixture was heated to 180.degree. C. to
allow the reaction to proceed for one hour. Furthermore, 172.8 g
(0.8 mol) of HCA was added to the flask to allow the reaction to
proceed at 180.degree. C. for two hours. Water was then removed
under heating and reduced pressure to obtain 504 g of a phenolic
resin (A-4) having a structural unit represented by structural
formula below.
##STR00018##
The obtained phenolic resin had a softening point of 142.degree. C.
(B&R method), a melt viscosity (measurement method: ICI
viscometer method, measurement temperature: 180.degree. C.) of 73
dPas, a hydroxyl equivalent of 536 g/eq, and a phosphorus content
of 11.2 mass %. The content of a component whose n=1 was 43.9%, the
content of a component whose n=2 was 30.1%, and the content of
components whose n=3 or more was 26.0% (the content of components
whose n=2 or more was 56.1%). FIG. 6 shows a GPC chart of the
obtained phenolic resin.
Example 5
Synthesis of Phenolic Resin (A-5)
[0157] A flask equipped with a thermometer, a cooling tube, a
fractional distillation column, a nitrogen-gas inlet tube, and a
stirrer was charged with 122 g (1.0 mol) of o-hydroxybenzaldehyde,
10.8 g (0.05 mol) of HCA, and 5.54 g (0.047 mol) of oxalic acid.
The mixture was heated to 120.degree. C. to allow the reaction to
proceed for two hours. Subsequently, 313.2 g (1.45 mol) of HCA was
added to the flask, and the mixture was heated to 180.degree. C. to
allow the reaction to proceed for three hours. Water was then
removed under heating and reduced pressure to obtain 415 g of a
phenolic resin (A-5) having a structural unit represented by
structural formula below.
##STR00019##
The obtained phenolic resin had a softening point of 84.degree. C.
(B&R method), a melt viscosity (measurement method: ICI
viscometer method, measurement temperature: 150.degree. C.) of 1.0
dPas, a hydroxyl equivalent of 420 g/eq, and a phosphorus content
of 10.5%. The content of a component whose n=1 was 86.7%, the
content of a component whose n=2 was 9.9%, and the content of
components whose n=3 or more was 3.4% (the content of components
whose n=2 or more was 13.3%). FIG. 7 shows a GPC chart of the
obtained phenolic resin.
Synthetic Comparative Example 1
Synthesis of Phenolic Compound (A-6) (the Compound Disclosed in PTL
2)
[0158] A flask equipped with a thermometer, a cooling tube, a
fractional distillation column, a nitrogen-gas inlet tube, and a
stirrer was charged with 122 g (1.0 mol) of p-hydroxybenzaldehyde,
216 g (1.0 mol) of HCA, and 336 g of 2-propanol. The mixture was
refluxed for five hours to precipitate a white solid. The white
solid was then filtered, washed with 1000 mL of 2-propanol, and
dried to obtain 325 g (yield: 96%) of a phenolic compound (A-6)
having a structure represented by structural formula below.
##STR00020##
FIG. 7 shows a GPC chart of the obtained phenolic compound.
Synthetic Comparative Example 2
Synthesis of Phenolic Resin (A-7) (the Compound Disclosed in NPL
3)
[0159] A flask equipped with a thermometer, a cooling tube, a
fractional distillation column, a nitrogen-gas inlet tube, and a
stirrer was charged with 236.6 g (0.7 mol) of the phenolic compound
(A-6) obtained in Synthetic Comparative Example 1 and 3.08 g (0.034
mol) of oxalic acid. The mixture was heated under stirring at
180.degree. C. for three hours. Water was then removed under
heating and reduced pressure to obtain 210 g of a phenolic resin
(A-7) mainly having a structural unit represented by structural
formula below.
##STR00021##
The obtained phenolic resin had a softening point of 84.degree. C.
(B&R method), a melt viscosity (measurement method: ICI
viscometer method, measurement temperature: 150.degree. C.) of 1.0
dPas, a hydroxyl equivalent of 420 g/eq, and a phosphorus content
of 9.4 mass %. The content of components whose n=2 or more was
34.0%. FIG. 8 shows a GPC chart of the obtained phenolic resin
(A-7).
Synthetic Comparative Example 3
Synthesis of Phenolic Compound (A-8) (the Compound Disclosed in PTL
4)
[0160] A flask equipped with a thermometer, a cooling tube, a
fractional distillation column, a nitrogen-gas inlet tube, and a
stirrer was charged with 169 g (0.5 mol) of the phenolic compound
(A-6) obtained in Synthetic Comparative Example 1, 47 g (0.5 mol)
of phenol, and 1.25 g of p-toluene sulfonic acid. The mixture was
heated to 180.degree. C. to allow the reaction to proceed at
180.degree. C. for eight hours. The reaction product was then
filtered and dried to obtain 199 g of a phenolic compound (A-8)
represented by structural formula below.
##STR00022##
The melting point of the obtained phenolic compound (A-7) was
286.degree. C. FIG. 9 shows a GPC chart of the obtained phenolic
compound (A-8).
Examples 6 to 10 and Comparative Examples 1 and 2
Test for Solubility in Solvent
[0161] Each of the phosphorus-containing oligomers (A-1) to (A-5),
the phenolic resin (A-7), and the phenolic compound (A-8) was
inserted into a screw-capped sample bottle in an amount of 50 g,
and then each of organic solvents was added thereto in such an
amount that the predetermined concentrations shown in Table 1 below
were achieved. After the mixture was stirred with a shaker at room
temperature, the state of the solvent in the bottle was confirmed
through visual inspection. Herein, a uniformly transparent state
was defined as a state of "dissolved", and a state in which a solid
component was precipitated or deposited was defined as a state of
"not dissolved".
TABLE-US-00001 TABLE 1 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 C. E. 1 C. E.
2 Solvent Concentration A-1 A-2 A-3 A-4 A-5 A-7 A-8 Methyl ethyl 50
mass % not not not not not not not ketone dissolved dissolved
dissolved dissolved dissolved dissolved dissolved 60 mass %
dissolved dissolved dissolved dissolved dissolved not not dissolved
dissolved 70 mass % dissolved dissolved dissolved dissolved
dissolved not not dissolved dissolved 1-methoxy- 50 mass %
dissolved dissolved dissolved dissolved dissolved not not
2-propanol dissolved dissolved 60 mass % dissolved dissolved
dissolved dissolved dissolved not not dissolved dissolved 70 mass %
dissolved dissolved dissolved dissolved dissolved not not dissolved
dissolved Ex.: Example C.E.: Comparative Example (The abbreviations
"A-1" to "A-8" in Table 1 denote the corresponding
phosphorus-containing oligomers, phenolic resin, and phenolic
compound.)
Examples 11 and 12 and Comparative Examples 3 to 6
[0162] Epoxy resin compositions were prepared in accordance with
formulations shown in Table 2 by a method described below and then
cured under the conditions below to experimentally produce
multilayer plates. The multilayer plates were subjected to various
evaluations. Table 2 shows the results.
[Preparation of Epoxy Resin Composition]
[0163] Epoxy resins, curing agents, and other components were mixed
in accordance with the formulations shown in Table 2, and then
compositions were prepared so as to finally have a non-volatile
content (N.V.) of 58 mass %.
[Conditions for Producing Multilayer Plate]
[0164] Base: 100 .mu.m; glass cloth "#2116" manufactured by Nitto
Boseki Co., Ltd. Number of plies: 6 Conditions for forming prepreg:
160.degree. C./2 min Copper foil: 18 .mu.m; JTC foil manufactured
by Nippon Mining & Metals Co., Ltd. Curing conditions:
200.degree. C., 40 kg/cm.sup.2, 1.5 hours Thickness of formed
plate: 0.8 mm
[Physical Property Test Conditions]
[0165] Glass transition temperature: measured by a TMA method
(compressive stress method) after an etching treatment was
performed to remove a copper foil. Temperature increase rate:
10.degree. C./min Combustion test: the test method was in
conformity with a UL-94 vertical test. Thermal delamination test
(T288 test): evaluation for thermal delamination resistance (with
copper foil) at 288.degree. C. was performed in conformity with IPC
TM650.
TABLE-US-00002 TABLE 2 Example Comparative Example 11 12 3 4 5 6
Epoxy resin N-690 53 54 67 34 40 FX-289BEK75 76 Curing agent A-1 27
27 A-2 A-7 66 A-8 60 TD-2090 20 19 33 24 Curing 2E4MZ (weight %)
0.1 0.1 0.1 0.1 0.1 0.1 accelerator Organic solvent MEK 72.4 72.4
72.4 72.4 72.4 72.4 Glass transition temperature (TMA) 150 146 183
Not Not 129 (.degree. C.) evaluated evaluated Thermal delamination
test (T288 >120 >120 >120 due to due to 0 test) crystal
crystal Flame Total combustion 28 32 -- precipitation precipitation
45 retardancy time (second) Combustion test V-0 V-0 Combustion V-0
class The abbreviations in Table 2 are as follows. N-690: cresol
novolac epoxy resin ("EPICLON N-690", epoxy equivalent: 215 g/eq)
manufactured by DIC Corporation FX-289BEK75: phosphorus-modified
epoxy resin ("FX-289BEK75", manufactured by Tohto Kasei Co., Ltd.:
epoxy resin obtained through a reaction between a cresol novolac
epoxy resin and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide,
epoxy equivalent: 330 g/eq, and phosphorus content: 3.0 mass %)
A-1: phosphorus-containing oligomer (A-1) obtained in Example 1
A-2: phosphorus-containing oligamer (A-2) obtained in Example 2
A-7: phenolic resin (A-7) obtained in Synthetic Comparative Example
2 A-8: phenolic compound (A-8) obtained in Synthetic Comparative
Example 3 TD-2090: phenolic novolac phenolic resin ("TD-2090",
manufactued by DIC Corportation, hydroxyl equivalent: 105 g/eq)
2E4MZ: 2-ethyl-4-methylimidazole
Example 1
[0166] A-2: phosphorus-containing oligomer (A-2) obtained in
Example 2 A-7: phenolic resin (A-7) obtained in Synthetic
Comparative Example 2 A-8: phenolic compound (A-8) obtained in
Synthetic Comparative Example 3 TD-2090: phenolic novolac phenolic
resin ("TD-2090", manufactured by DIC Corporation, hydroxyl
equivalent: 105 g/eq) 2E4MZ: 2-ethyl-4-methylimidazole
* * * * *